The panel, so called LCD (Liquid Crystal Display), is a common electronic display device. The present panel such as GOA (Gate driver on Array) panel is instantly powered off, the liquid crystal capacitor of the panel cannot be completely discharged. Such incomplete liquid crystal capacitor can cause the panel display ghost.
For solving the issue of the panel display ghost, the prior art provides a panel signal control circuit. Please refer to FIG. 1. The panel signal control circuit provided by prior art comprises: a PWM IC (Pulse-Width Modulation Integrated circuit) 10 and a level shift IC 11. Please refer to FIG. 2. FIG. 2 is a signal diagram of respective signals of the circuit in FIG. 1. VGH and the TFT (Thin Film Transistor) in panel control the electrode high voltage level. VGH is also the output working voltage of the PWM IC. XAO can be a voltage inversion signal inputted to the level shift IC after the GOA panel is powered off and the PWM IC stops working. After the level shift IC receives the XAO signal, the Discharge function is activated. The Discharge function specifically comprises: synchronizing respective output CK (clock) signals with the VGH signal, and after synchronization, the respective output CK signals drops along with the descend of VGH. As shown in FIG. 2, after the GOA panel is powered off, VGH remains to be high voltage level in a period of time. The respective output CK signals are synchronized with VGH, thus the TFTs coupled to the respective output CK signals still can be in the activation state to make the rest electric charge on the liquid crystal capacitor is released to ground through the activated TFTs. Consequently, the liquid crystal is discharged to eliminate the panel display ghost.
In the solution of realizing prior art, the following technical issue is found:
Please refer to FIG. 2. Because the respective output CK signals are synchronized with VGH, the voltage value of VGH has already been dropped, and the voltage values of the respective output CK signals synchronized with VGH also will drop. Accordingly, the voltage values of the respective output CK signals are insufficient, and the time period that the TFTs coupled to the respective output CK signals cannot be activated or activated gets short. The discharge of the liquid crystal capacitor is incomplete, and the elimination of the panel display ghost is incomplete.